THE BACTEROIDS. 347 



F. NOBBE, E. SCHMID, L. HiLTNER, and E. HOTTER (II.), the nodule 

 bacteria of Elceagnus differ greatly from those of the Legu- 

 minosce. 



These observations are also of importance to practical agri- 

 culture. Already, for several years past, soils intended to be 

 brought under cultivation (e.g. high moorland soils) for the growth 

 of nitrogen-collecting plants are previously inoculated, i.e. strewn 

 with a little earth from fields that have borne leguminous plants 

 for a long time,, and are consequently rich in nodule-forming 

 bacteria. For this inoculation to have the desired result, it is 

 necessary to use earth containing the bacterial species most efficient 

 for the kind of Leguminosce to be afterwards grown. Practical 

 experience on the importance of this consideration is already avail- 

 able. Thus SALFELD (L) has reported that a similar soil intended 

 for peas could not be rendered capable of yielding a crop unless 

 strewn with a little soil obtained from a good pea-field, soil from 

 a lupin-field failing to produce the desired effect. A similar dis- 

 covery was made by M. FLEISCHER (L). This treatment must, of 

 course, be preceded by any improvement found necessary in the 

 chemical composition of the soil. Thus, for example, sour moor- 

 land must previously be limed, in order to neutralise the acids 

 preventing the development of the nodule bacteria. Moreover, 

 this operation must be performed with discretion, an excessive 

 addition of lime being avoided. Reference may be made on this 

 point to a communication by TACKE, IMMENDORF, HESSENLAND, 

 and MINSSEN (L). 



195. The Bacteroids. 



The bacteria in question are often met with in air and water, 

 and very frequently in the soil. NOBBE, SCHMID, HILTNER, and 

 HOTTER (I.) made several quantitative bacteriological investiga- 

 tions on this point. The bacteria pass from the soil into the roots 

 of such plants as will admit them. The first successful artificial 

 production of nodules by the aid of pure cultures was made by 

 A. PRAZMOWSKI (IV.). This worker, in view of the absence of 

 the sporogenic faculty in these organisms, changed the name of 

 Bacillus radicicola, bestowed on them by Beyerinck, into Bac- 

 terium radicicola. According to his observations, this fission 

 fungus penetrates the epidermal cells of the root-hairs, and there 

 develops to a colony which then surrounds itself with a tough 

 membrane. From this original position there branches out a 

 lustrous sac, filled with bacteria, which turns towards the bark 

 cells and branches out amongst them. As a result of this advance 

 towards the centre of the root-hair, the cells thereof are incited 

 to rapid increase and become densely crowded, in consequence 

 of which they assume a polygonal outline, and constitute the 



